Templates classification

Woolfson and Mahmoud have classified the routes to preparation of decorated self-assembling peptide materials [53] as (1) co-assembly, where the functional part is already attached to a self-assembling component prior to assembly, and (2) postassembly, where a non-functionahsed self-assembled structure is modified by covalent or non-covalent means. This discussion adheres to this classification. A third route, beyond the scope of this review, is the use of structured peptides as templates for inorganic materials. Section 4.1 discusses functionalised self-assemblies formed from co-assembly-type approaches, while post-assembly modifications of self-assembled structures are considered in Sect. 4.2. 

Fig. 3. Classification of human prion diseases. Sporadic the transformation from PrPc (circle) to PrPSc (square) occurs without apparent cause. Familial a point mutation ( ) is thought to facilitate the transformation. Infectious the transformation arises via PrPSc which acts as a template. The kinetic equations are defined by Eigen (1996). The infectious form includes kuru, iatrogenic CJD (iCJD), variant CJD (vCJD first reported in 1996), bovine spongiform encephalopathy (BSE first reported in 1985), and scrapie. In the nucleation-dependent model, monomeric PrPc and PrPSc are in chemical equilibrium.

The complex spatio-temporal mosaic of habitats in alpine river systems relates to the interaction of a range of physicochemical processes, with different processes dominating the river environment at different scales. Our new approach to alpine stream classification provides a basis to conceptualise this dynamic habitat template. The contributions from the different water sources have an important influence on the aquatic habitat template for the establishment of biotic communities, particularly through the effect on physicochemical variables outlined above. These include channel stability, water temperature and sediment regimes. Where alpine streams... 

The molecules that form the foundation of living systems are often organized into four categories. They are the primary metabolites nucleic acids, proteins, carbohydrates, and lipids. The categories can be grouped together in different ways, based on features that they have in common. For example, nucleic acids, proteins, and polysaccharides are polymeric. Nucleic acids and proteins are further related because they are templated polymers. Other classification systems are also possible.1 Interest in the development of size-expanded versions of biomolecules has grown over the past... 

Many studies that have focused on the formation mechanism of various types of templated mesoporous materials have been summarized in a number of recent reviews,46 9 and it is still an ongoing topic of research.50 51 Here, we want to recapitulate only very briefly the useful interaction classification scheme between the surfactants (S) and the inorganic species (I), which was suggested by Huo et al.52,53... 

Whereas the classification of the previous section was by ligand type and donor set, the present section presents the material grouped by the identity of the central metal, in order to facilitate comparisons of reactivity. The discussion will concentrate on the metal ions Zn, Cu, Ni, Co, and Fe, and on ligands with a predominance of nitrogen donor atoms. More elaborate ligand structures derived from 1 by templated condensation reactions are not covered by this review (24-28). The same applies to ligands with N04 (29), NS4, and NP4 donor sets (30), for which the reader is referred to the literature. 

To date, two different OCR methods were implemented in CLiDE. The first one used a back-propagation neural network for classification of the characters. The character features used as input to the neural network are determined by template matching (Venczel 1993). The second OCR implementation in CLiDE is based on topological and geometrical feature analysis, and it uses a filtering technique for the classification of characters (Simon 1996). 

In summary, chiral solvents have only induced limited enantioselectivity into different types of photochemical reactions as pinacolization, cyclization, and isomerization reactions. These studies are nevertheless very important, because they are among the early examples of chiral induction by an asymmetric environ ment. Based on our classification of chiral solvents as chiral inductors that only act as passive reaction matrices, effective asymmetric induction by this means seems to be intrinsically difficult. From the observed enantioselectivities it can be postulated that defined interactions with the prochiral substrate during the conversion to the product are a prerequisite for effective template induced enantioselectivity. 

In terms of imprinting in polymers essentially the only class of templates used to date are low molecular weight compounds which are predominantly convex in shape. Clearly other opportunities remain available. Fig. 7 summaries the classification scheme for templates. 

A great diversity of approaches has been followed to develop MIM sensors. We have found it helpful to apply three complementary classifications to these approaches (i) the nature of the transducer employed in the sensor (ii) the nature of the MIM (iii) what is measured a property of the analyte (the MIM serving simply to concentrate the analyte near the transducer), a property of the MIM which changes upon interaction with the analyte, or a second messenger, whose concentration is dependent on the analyte interacting with the MIM. It is often difficult to assign a material as molecularly imprinted or not. Thus, we use the expression MIM here to refer to materials which are designed to rebind the template used in their preparation and refer to other materials where the template and the subsequent analyte differ as templated materials. 

In this review, nanoporous dielectric materials have been presented. The preparation techniques, methods of pore generation, and materials classification were discussed. Inorganic, organic, and hybrid films were also discussed. The nanoporous dielectric films were classified by preparation method, which includes block copolymer, solvent as porogen approach, surfactant templating, and sol-gel approach. This is still a very active field of research because no one film has satisfied all the stringent requirements in semiconductor device processing. 

There are different ways to categorize templates. One could for example try to distinguish template effects according to the (non-)covalent interactions involved. This classification remains ambiguous for templates operating through different forces at the same time. A maybe better way to classify templates relates to their topography. The early templated crown ether syntheses utilized alkali metal ions... 

Once these questions can be answered within the TAR model, a rational design of template effects may become possible. The mechanism presented may already be useful as a helpful classification scheme to incorporate the tremendous variety of empirically found template-assisted chemical processes. The elementary steps sketched so far can be supplemented by reaction rate constants, which can be combined to a final formal-kinetic scheme to yield the total reaction rate. As a consequence, predictive elements of the TAR model will show up. 

Finally, we argued for the elaboration of a thermochemical model, i.e. the TAR model, to embrace as many of the various empirically found host-guest and template-assisted processes as possible. Apart from the classification-type nature of a decomposition into elementary steps in such a model, it automatically assigns enthalpies and entropies to these steps to be calculated with theoretical methods and to be then compared to experimental measurements as described in Section 12.2.5. Last but not least one may even apply formal kinetics to derive general statements of rate constants on the individual steps as well as on the overall process. 

Classification of the major supramolecular templating routes according to surfactant charge... 

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